Almost all double-coated pressure-sensitive adhesive tapes are wound up with disposable, low-adhesion liners which are discarded when the tapes are unwound for use. Many double-coated tape dispensers are equipped to wind up the liner as the tape is dispensed. This not only makes the dispenser more expensive and awkward to handle, but the user must occasionally take the time to discard the wound liner. Disposal of the liner is especially troublesome in robotic systems.
U.S. Pat. No. 2,889,038 (Kalleberg) discloses a linerless double-coated pressure-sensitive adhesive tape wound upon itself in roll form and comprising a flexible support having on opposite faces chemically different and physically incompatible pressure-sensitive adhesive layers. Although the Kalleberg patent calls both layers "aggressively tacky", the patented linerless transfer tape is not currently used when high performance is required. Even though Kalleberg tapes are currently on the market, it is believed that at the present time all double-coated pressure-sensitive adhesive tapes which have high performance are wound up with disposable, low-adhesion liners. Furthermore, the adhesive layers of the Kalleberg tapes being marketed have a mottled appearance, and it usually is necessary to limit the thickness of each layer to about 0.1 mm.